The goals of this proposal are 1) to develop a better understanding of the pathogenesis of postoperative infections, 2) to identify ways of decreasing the frequency of these infections and 3) to analyze critically the excess costs attributable to infections and to infection-prevention practices. We feel that effective control measures must be predicated upon a sound understanding of the epidemiology of postoperative infections. We have designed studies to investigate the interactions between host risk factors, surgery, and bacterial colonization or contamination. We have developed a method of obtaining quantitative, cultures from moist surfaces which will enable us to study the role of intraoperative wound contamination on the incidence of postoperative would infection. We will also use this technique to evaluate the impact of an intraoperative wound infection. We will also use this technique to evaluate the impact of an intraoperative infection control technique to limit the frequency or magnitude of wound contamination. Other clinical studies will evaluate the efficacy of other infection control programs, such as nutritional support teams or "awareness" techniques, to reduce rates of postoperative infections. All of our control studies will evaluate the direct costs of the intervention technique as well as the infection-to-be-prevented. We will focus directly on studies of misuse of prophylactic perioperative antibiotics and evaluate the impact of an intervention program which will attempt to correct the problem and reduce costs of surgery. Our long term objective is to identify effective and cost-efficient ways to reduce the incidence of postoperative infections.